The present invention relates to an integrated chuck system for a lathe which is comprised of a number of components and can be mounted on the machine spindle of a lathe for engagement with a workpiece and for disengagement from the workpiece. More particularly, the invention relates to a chuck system of this type which has, in addition to a jaw chuck whose jaws may be moved into and out of engagement with the workpiece, an actuating cylinder for shifting the jaws of the chuck, a multiple medium feed device for distributing a hydraulic medium to the cylinder, and a stroke-control system for monitoring the axle position of the piston of the actuating cylinder and thus the positions of the jaws of the chuck.
Fine-adjustment and automatic or powered lathe chucks, so-called integrated chuck systems, have been provided heretofore for lathes and have generally comprised the jaw chuck itself which is provided on the chuck body. This chuck is usually mounted on the free axially front end of the lathe or machine spindle so that it can rotate with the latter.
In modern lathes, the machine spindle is often directly driven and frequently can be constituted as a hollow spindle.
The jaws of the chuck have in the past been controlled by an actuating cylinder to which a hydraulic fluid can be fed by a multiple medium feed unit also mounted, as described in DE 196 52 664, on the spindle, but usually at the rear end thereof. The stroke-control system, if provided, likewise is mounted at the rear end of the spindle. The result is an axial stacking of the chuck at one end of the spindle, the spindle between the ends thereof, and the actuating cylinder, the multiple-medium feed device and the stroke-control system at the opposite axial end of the spindle such that the length dimensions or the dimensions of these elements in the axial direction and in the machine. The result is a lathe head which is very long and, in the case of so-called synchronized spindle machines which are used for bearing machines in crank shaft production, creates an overall machine length which is problematical. Since the plant must provide space for such machines and space is at a premium in these plants, problems have been encountered.
It is the principal object of the present invention to provide a so-called integrated chuck system, i.e. a fine-adjustment automatic or powered chuck system of the aforedescribed type, having in addition to the chuck body and the jaws, an actuating cylinder and a stroke-control system with a monitor for the piston position of that cylinder, whereby the spatial requirements are reduced.
Another object of this invention is to provide an improved chuck system of the aforedescribed type which is free from drawbacks of the prior art.
These objects and others which will become apparent hereinafter are attained, in accordance with the invention by integrating one or more of the components associated with the chuck in the chuck system within the hollow spindle. According to the invention, the component or components which are integrated within the hollow spindle can be the actuating cylinder and its piston or pistons, the stroke-control device and/or the position sensor for the position of the piston of that cylinder.
According to the invention, the hollow spindle has an internal diameter which is sufficient to accommodate the component or components received therein. The components may be individually or collectively received in the hollow spindle.
The invention thus provides the advantage that the overall length of the head of the lathe is no longer the additive combination of the lengths of the chuck body, the spindle and the other components mentioned since these components are in whole or in part incorporated into the hollow spindle.
Most advantageously the hollows spindle accommodates within its interior and between its ends, the actuating cylinder and the multiple medium feed device.
According to a feature of the invention, the ends of the actuating cylinder and the multiple medium feed device which are turned toward one another are so configured that they can mutually engage after they are inserted from opposite axial ends into the machine spindle and meet within the spindle between the ends thereof.
The chuck, actuating cylinder, multiple medium feed and stroke-control system can be combined in a complete system on a lathe spindle in which the actuating cylinder, multiple medium feed device and the stroke-control system, together with the sensor for the position of the piston and that cylinder are all located within the spindle.
The assembly, when constructed in this manner, has the embodiment advantage that access is only required to one end of the machine spindle since the application of the chuck body to the end of the spindle is the only work required at the spindle end.
Advantageously, between the piston of the actuating cylinder and the chuck, a bayonet coupling is provided and the chuck can be provided with fastening means for securing the chuck body to the actuating cylinder. In this embodiment, it may be desirable to push the actuating cylinder into the machine spindle and to secure it provisionally in place so that it can be connected by a bayonet coupling with the chuck, thereby affixing the assembly to the chuck and the actuating cylinder to the machine spindle.
From the point of view of further shortening, the axial length of the total system and the head of the lathe, the stroke-control system can be included at least over part of its length in the hollow spindle and the degree of integration of the components in the hollow spindle over the system in which only the actuating cylinder and the medium distribution device are received therein, is thereby greater.
The multiple medium distributor can be mounted on the stroke-control rod and inserted into the hollow cylinder together with it. Advantageously, the distributor housing can be held against rotation by the stirrup which carries the sensor of the stroke-control system. The stirrup thus holds the distributor against rotation by the spindle.
The power chuck assembly for a lathe according the invention thus can comprise:
a hollow lathe spindle;
a jaw chuck affixed on one end of the spindle and comprising a chuck body and jaws movably mounted on the chuck body;
an actuating device for the jaws of the chuck including an actuating cylinder having a piston operatively connected to the jaws;
a multiple medium feed device for supplying hydraulic fluid to the actuating cylinder; and
a stroke control device including at least one sensor for a position of the piston an thereby of the jaws, at least one of the devices being integrated into and received in an interior of the hollow spindle, the spindle having an inner diameter enabling the one of the devices to be accommodated in the spindle.
The hollow spindle therefore has an inner diameter sufficient to accommodate the actuating cylinder and multiple medium feed device which are both received in the hollow spindle. The mutually facing ends of the actuating cylinder and the multiple medium feed device are provided with connecting means for interconnecting the actuating cylinder and the multiple medium feed device and enabling insertion of the actuating cylinder and the multiple medium feed device into the hollow spindle from opposite ends thereof.
The chuck and piston are connected by a bayonet connection and preferably the stroke-control device extends over at least part of its length in the hollow spindle.